Carton



June 23, 1964 R. F. REIFERS ETAL 3,13

CARTON aluminum .mm nw mnuw l unmuu 2o 6 se Use a .42

Ri 0rd E Reife nry A. Lo

FIG.9. I INVENTOR ATTORNEY June 1964 R. F. REIFERS ETAL 3,133,313

CARTON Filed Feb. 5, 1962 2 Sheets-Sheet 2 INVENTOR Richard F. Reifers &

Henry A.Lord

W ATTORNEY United States Patent 3,138,313 CARTON Richard F. Reifers, NewCanaan, Conn., and Henry A. Lord, Palmer, Mass., assignors to DiamondNational Corporation, New York, N.Y., a corporation of Delaware FiledFeb. 5, 1962, Ser. No. 171,174 8 Claims. (Cl. 2292.5)

This invention relates generally to containers and more particularly toimprovements in molded pulp articles and methods of affording suchimprovements.

Typical containers of the character involved are disclosed in US.Letters Patent to Reifers #2,888,183, issued May 26, 1959, which aredesirable for the purpose intended. However, there has been a continuouseffort to attain greater strength per weight of pulp fiber used duringthe manufacture of containers or cartons of the character involved, morepositive locking, and structural strength in the movable parts which aresusceptible to mechanical deformation.

Additionally, there is a continuous efi'fort to improve manufacturingtechniques whereby conventional equipment can be used and the qualityand performance of the product can be increased without increased costin the production of the product or substantial modification to theconventional apparatus.

A primary object of the present invention is to provide an improvedmolded pulp carton which affords greater dimensional control of thefinished carton, especially during drying, provides pre-stressing incertain carton sections that may be subject to mechanical deformationwhen manipulated during opening or closing of the carton, and whichsubstantially eliminates the natural direction of warpage of relativelythin planar sections of the carton to maintain the various cooperatingparts in an optimum oriented position.

Another object of this present invention is to provide novel lock meansin cartons of the character involved which provides a double lock.

A still further object of the present invention is to provide a novelmethod of pre-stressing integrated pulp fiber of an article preform forresisting mechanical deformation which occurs during manipulation of thecooperating parts of the lock structure of the carton.

Although the exemplary embodiment of the invention is disclosed inrelation to molded pulp egg cartons, the principles of the invention arereadily adaptable to other types of cartons generally having the samestructural and functional characteristics as that illustrated by theabovementioned prior art patent.

Other objects and the nature and advantages of the instant inventionwill be apparent from the following description taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a fragmentary bottom plan view of the bottom section and lockflap of a carton incorporating the features of the invention;

FIG. 2 is a front elevation of the carton of FIG. 1, prior to the cartonbeing closed;

FIG. 3 is a fragmentary vertical section taken substantially on theplane of line 33 of FIG. 2, showing by phantom lines the manner in whichthe lock flap cooperates with the lid section when the carton is closed;

FIG. 4 is a section taken substantially on the plane of line 44 of FIG.2, showing by phantom lines the relative position of a portion of asuction mold screen, and illustrating the three-dimensional reinforcingand prestressing ribs of the lock flap;

FIG. 5 is a front elevational view similar to FIG. 2, showing anotherembodiment of a carton incorporating the features of the invention andillustrating a novel double-lock used in the carton;

Patented June 23, 1964 FIG. 6 is a vertical section taken substantiallyon the plane of line 6-6 of FIG. 5, and similar to FIG. 3;

FIG. 7 is a front elevational view similar to FIGS. 2 and 5 showing afurther embodiment of the novel carton incorporating the features of theinvention;

FIG. 8 is a vertical section taken substantially on the plane of line8-8 of FIG. 7, and similar to FIGS. 3 and 6; and

FIG. 9 is a fragmentary perspective view of the lock flap of FIG. 7,illustrating by means of direction arrows the manner in which the lockflap is pre-stressed when it is produced.

The present invention is shown in relation to an egg carton or similarcontainer which incorporates a bottom section, lid section and lock flapsection, the lid and lock flap sections being articulated with respectto the bottom section so that they will automatically snap lock togetherin a closed condition, and yet be readily and quickly released foraccess to the carton contents without inverting the carton.

Referring to the drawings, a molded pulp carton is indicated generallyat 10 in FIG. 2 and includes a bottom section 12 formed as a 3 X 4 stylemolded pulp carton for containing eggs, for example. The carton ismolded in any suitable manner, and includes along a forward longitudinaledge a hinge structure 14 connecting thereto a lock flap indicatedgenerally at 16 which is normally biased forwardly of the carton edge toafford a snap-lock function when in a locked condition. Hingedlyconnected at 18 to the opposite side margin of the bottom section 12 isa lid section indicated generally at 20 which includes a planar top wall22 and depending rear and front walls 24 and 26, respectively, formedintegral with side walls 28 and 30. The bottom section 12 includes aperipheral upper margin 32 abuttingly engaged by the peripheral margin34 of the top section 20.

The flange 32 is relieved or notched out as indicated at 36 and 38 atopposite ends of the lock flap 16 and a hinge or articulated connection14 to permit free pivoting of the lock flap 16 toward a locking andunlocking position.

The manner in which the exemplary embodiment of the carton functions isdescribed in detail in the previously mentioned Us. Letters Patent#2,888,183, and accordingly further description of the manner in whichthe carton functions is believed to be unnecessary.

The lock flap of the embodiment shown in FIGS. 1-4 includes asubstantially planar base 40 comprising a single thickness or layerpaper pulp fiber having integrated therewith substantially threedimensional pre-stressing and reinforcing ribs indicated generally at42. The ribs 42 are disposed symmetrically with respect to a laterallyprojecting abutment or lock button 44 which extends substantiallynormally from the planar base 40. The outer edges of the lock button 44are relieved or rounded as indicated at 46 and it is formed with aslight undercut notch or groove 48 for the purpose of positivelysecuring the carton in closed condition. The lock button 44 is disposedinwardly or below the upper edge 50 of the lock flap base 40 to preventdistortion of the carton preform during vacuum transferring of the wetpreform from a molding die to transfer dies or drying dies, for example(not shown).

Positioned beneath the lock element or abutment 44 is a reinforcing andpre-stressing portion 52 which extends out of the surface of the planarbase 40 and which is substantially three-dimensional.

The pre-stressing and reinforcing ribs 42 include a plurality ofangularly extending, symmetrically disposed rib elements or portions 54,56 and 54', 56', the rib elements 54, 56 and 54', 56 being mutuallyparallel. Extending from the hinge connection 14 are a plurality ofreinforcing feet 58, 60, 62 and 64 disposed in symmetrical relationshipto reinforcing feet 58', 60, 62 and 64', respectively. The feet 60, 62and 64, as well as the feet 60', 62 and 64 are formed integral withmutually parallel leg elements or ribs 66, 68 and 79 and 66, 68 and 70',which terminate at the ends of the angularly disposed rib elements 54,56 or 54', 56'.

In a finished carton, the rib elements will resist bending in both avertical and horizontal plane parallel to the hinge 14 or normalthereto, and this function is afforded by the angular relation of therib element 54, 56 and 54, 56 with respect to the normal bending planesof the planar base 40.

The rib elements have a dual function which affords positive orientationor dimensional control of the abutment lock element 44 duringmanufacture of the carton, as well as reinforcing by pre-stressing thefiber during the manufacture of the carton. When the lock flap 16 isinitially deposited as a layer of pulp fiber on a wire screen asindicated by S in FIG. 4, the screen will have formed therein grooves Gwhich will fill up with the fiber and build over to form the ribelements which will be integral with the substantially planar base 40and have a threedimensional configuration as clearly seen in FIG. 4.

Considering the prior art disclosure, Us. Letters Patent #2,88S,l83, itwill be noted that the lock flap therein is substantially planar. It hasbeen observed during the manufacturing process that when this carton wasproduced, the substantially planar lock flap tends to warp or bow awayfrom the screen side of the preform inwardly during drying of the cartonpossibly due to fiber impaction adjacent the screen side of the preform.Such drying or warpage sometimes tends to disorient the lock flap buttonto such a degree that the carton will not lock initially, or would bereadily opened during handling or transport.

The relatively thin planar section of the prior art lock flap tends todry more rapidly than the bottom or lid sections.

Utilizing the principle of pre-drying of a relatively thin section ofmolded pulp, an unusual phenomenon occurs by incorporatingthree-dimensional rib structures on the planar section. As clearlyillustrated in FIG. 9, after a carton preform is deposited on a suctionmold, and removed therefrom for the purpose of permitting it to dry, thelock flap 16 will dry first, then the lid section 20, and then therelatively thick bottom section 12 dries last. Referring particularly tothe drying action which occurs in the lock flap section 16, the planarbase 40 initially dries and becomes substantially set, pulling the pulpfiber of the rib elements 42 together or compressing the same inasmuchas this portion is still damp, although the planar base 40 is dried. Theinitial drying action of the planar base 40 tends to cause bowing of thelock flap on the screen side. However, when the rib elements 42, whichare substantially three-dimensional and solid, dry, they shrink and pulltogether. When this occurs, the planar base 40, which is already dry,and the drying of the rib elements actually pre-stress the planar base40 and imposes therein internal tension which tends to flatten theplanar base 40 to a degree wherein the previously undesirable warpage orbowing is substantially eliminated.

Further, in addition to maintaining the planar base 40 in asubstantially single plane, by disposing the rib elements 42 symmetricalto the lock button 44, the lock button 44 is maintained in asubstantially pre-selected position, and thus dimensional requirementsof the lock flap are maintained within prescribed limits. Still further,by pre-stressing the planar base 40 by virtue of the drying of the ribelements 42, the lock flap 16 is internally pre stressed to resistmechanical deformation in the normal bending planes of the lock flap toprevent mechanical deformation during opening and closing of the carton.

Referring to the lid section 26, it will be noted that an aperture 72extends transversely through the forward wall 26 thereof and into thetop wall 22. As seen in FIG. 3, and as illustrated by the solid phantomlines, the lock flap 16 is inserted adjacent the inner surface of thetop wall 26 of the lid section 20 and the undercut lip or groove 48 willengage over the abutment edge 74 of the aperture 72 in the lid section.The portion 52 immediately below the lock button 44 not only aids inpro-stressing the planar base 40, but also provides an abutmentimmediately below the groove 48, see FIG. 3, which maintains the forwardwall 26 of the carton in a position whereby after the carton is lockedin the manner shown in FIG. 3 by phantom lines, the lock button 44 maybe readily pushed through the aperture 72 in the forward wall 26 of thelid section to permit ready release of the lid from the lock flap. Thebottom section 12 includes a centrally located abutment 15 having avertically projecting edge 17 adjacent to the hinge structure 14 andengageable by lock flap 16 tending to urge the lock button 44 intolocked engagement in the aperture 72 of the wall 26 of the lid sec tion14; see dotted lines FIG. 3.

Referring to FIGS. 5 and 6, another embodiment of a carton including thenovel features previously mentioned, is indicated generally at 100. Thiscarton includes a bottom section 112, having hingedly connected at 114 alock flap indicated at 116. Hingedly connected at 118 to the rear upperperipheral edge of the bottom section 14 is a lid section 129. Thebottom section 112 includes an upper peripheral flange 132 abuttinglyengageable by a peripheral flange 134 of the lid section 120.Additionally, the lid section 120 includes a substantially planar topwall 122 and depending forward and rear side walls 126 and 124,respectively, and end walls 128 and 130.

In this embodiment of the invention, the lock flap 116 incorporatesthereon reinforcing and prestressing rib elements indicated generally at142 and extending from a substantially planar base 140. Additionally,the lock flap 116 has formed thereon an abutment or lock element 144which is the structural and functional equivalent of thte similarlydescribed structure of the embodiment of FIGS. 1 through 4. In thisembodiment of the invention, the planar base includes a lock nose orextension portion 147 which projects a greater distance above the lockelement 144 than the comparable portion 50 of the embodiment of FIGS. 1through 4.

The top section 120 has a transverse aperture 172 which extends agreater distance rearwardly into the top wall 22 to form a rear abutmentedge 176. The transverse aperture 172 forms in the forward wall 126 alower lock edge 174 comparable to that previously mentioned.

It will be readily observed that when considering the solid and phantomline views illustrated in FIG. 6 the lock extension 147 will projectupwardly and in front of the lock edge 176 of the top wall 172 at thesame time that the lock nose 144 extends over the lower abutment or lockedge 174 formed by the aperture 172 which extends through both theforward wall 126 and the top wall 122. Thus, if a forward rolling actionis imposed on the top section 120, the lock tongue or extension 147 willresist movement of the top section forwardly with respect to the lockflap 116.

In the absence of the reinforcing and prestressing ribs 142, a doublelock comprising the lock nose 144 and the lock tongue 147 is provided.

Referring to FIGS. 7 and 8, a still further embodiment of a carton isindicated generally at 210, this carton comprising a bottom section 212,a hinge connection 214, and a lock flap 216. A top section 220 ishingedly connected at 218 to the rear upper peripheral margin of thebottom section 212. The top section forward wall 226 and top wall 222have extending therethrough an aperture 272 which includes a relieved orfilleted lower corner structure as indicated at 273, and a lowerabutment edge 274.

The lock flap 216 includes reinforcing rib and prestressing elements 242which are integral and project from a substantially planar base 240.Generally speaking, the pie-stressing and reinforcing rib elements 242are substantially the same as, and the functional equivalent of, thosepreviously described. However, in this embodiment, a reinforcing element252 is provided, which it has been found relieves the stresses andmaintains orientation of the abutment lock or nose element 244 formedintegral with the base 240 and projecting laterally therefrom.Additionally, the upper rib elements 254 and 254' include leg portions255 and 255', respectively, terminating in inwardly extending portions257, 257, respectively, which terminate at opposite sides of the locknose or abutment element 244. This structure not only reinforces butprestresses the base 240 immediately adjacent the lock nose 244 tosubstantially rigidify the lock flap 216 and permit continued use of thecarton lock structure without any substantial mechanical deformationduring manipulation of the novel carton.

Briefly referring to FIG. 9, to review the novel principles andfunctional characteristics of the invention, it will be observed thatthe novel lock flap and cooperating structure is formed by the method ofpermitting the substantial planar base of the lock flaps of thedisclosed embodiments to dry prior to the drying of the reinforcing orpre-stressing rib elements. It will be noted that the direction arrowsof FIG. 9 indicate the early drying of the planar base 240, for example.When this drying occurs and accompanying shrinkage also occurs, therelatively compact three dimensional pre-stressing and reinforcing ribelements 242 will attempt to shrink along their length but aremaintained in a relatively fixed position by the already pre-shrunk base240. Thus, as indicated by the dotted direction arrows of FIG. 9,internal pre-stressing results, which tends to pull the lock flap 216from a bowed condition to a substantially flat condition, internallyprestress the base 240.

It is within the purview of the art that the reinforcing rib elements beincorporated on the side of the lock flap opposite that shown, dependingon the condition of control one would desire with respect to projectingor locking elements of various cartons.

As previously mentioned, the manner in which the car ton is manipulatedis explained in detail in US. Letters Patent #2,888,l83 and furtherdescription of the manipulation of the carton parts in order to open orclose the carton is believed to be unnecessary.

It will be obvious to those skilled in the art that various changes maybe made without departing from the spirit of the invention and thereforethe invention is not intended to be limited to what is shown in thedrawings and described in the specification, but only as set forth inthe appended claims.

What is claimed is:

1. A molded pulp carton including a bottom section having opposedmargins, a lid section and a lock flap section hingedly connected tosaid opposed margins of said bottom section, and cooperating lock meanson said lid and lock flap sections, said lock means comprising aperturemeans on said lid section and lateral abutment means on said lock flapsection; the improvement wherein said lock flap section includespre-stressed fiber portion intermediately of the hinge connection ofsaid lock flap section and said lateral abutment means for resistingtension and bending deformation of said lock flap section when thecooperating lock means is operated and maintaining said lateral abutmentmeans in dimensionally oriented relationship to said aperture means,said lock flap comprising a substantially planar base having saidpre-stressed fiber portion integrally formed therein, said abutmentmeans projecting out of one surface of said planar base, and said planarbase including pre-stressing rib elements projecting out of one surfacethereof, said rib elements extending between the hinge connection ofsaid lock flap and terminating adjacent said lateral abut ment means,said rib elements being disposed symmetrical to said abutment means andextending in spaced parallel relationship with respect to each other andin angular relationship with respect to said hinge connection.

2. A molded pulp carton as set forth in claim 1 Wherein said ribelements are disposed in longitudinally spaced parallel relation alongsaid hinge connection, symmetrically with respect to said lateralabutment means and terminate adjacent said hinge connection of the lockflap and at said abutment means.

3. A molded pulp carton as set forth in claim 2 wherein certain of saidrib elements terminate in parallel foot portions.

4. A molded pulp carton as set forth in claim 3 wherein an opposed pairof said structural elements include terminal portions integrated atopposite ends with said lateral abutment means.

5. A one-piece carton including a bottom section having opposed upperside margins, a lid section including a substantial planar top anddepending opposed side wall portions and including lower marginsjuxtapositionable on the upper side margins of said bottom section, saidtop section being hingedly connected to one opposed upper side margin ofsaid bottom section, a lock flap hingedly connected to another opposedupper side margin of said bottom section opposite that to which said lidsection is connected and normally biased forwardly from said bottomsection, said lid and lock flap including cooperating lock meansdetachably connecting said lid section in juxtaposed relation on theupper margin of said bottom section with said lock flap juxtaposed onthe inner surface of the forward side Wall portion of said lid section,the improvement comprising a lateral lock-abutment projectingintermediately from one side of said lock flap, said lock flap includinga lock-extension extending above said lockabutment, said lid includingan aperture portion extending through said planar top and the forwardside wall portion adjacent the juncture thereof, said aperture portionincluding an upper edge abuttingly engageable with said lock-extensionand a lower edge engageable beneath said lock-abutment.

6. In a carton including a bottom section having an upper peripheralportion, and a lock flap lid section hingedly connected on parallelhinge axes at opposite sides of said bottom section and resilientlyurged toward planar relation with respect to a plane passing throughsaid upper peripheral portion of said bottom section, the improvementcomprising locking means including cooperating portions on said lid andlock flap sections, said lid section including an intersecting top andforward wall, an aperture portion extending through the intersection ofsaid top and forward walls and forming abutment edges in the plane ofsaid top wall and said forward wall, said lock flap section including anintermediate abutment projecting from one side thereof and removablyreceived in said aperture portion and engageable over the abutment edgein said forward wall, said lock flap including a lock extension in thegeneral plane thereof disposed above and behind said intermediateabutment for engaging in front of the abutment edge in said top wall.

7. In a carton as set forth in claim 6 wherein said lock flap includes apre-stressed fiber portion beneath said intermediate abutment forstabilizing said lock flap against mechanical deformation.

8. In a carton as set forth in claim 7 wherein said lock flap sectioncomprises a substantially planar base from which said intermediateabutment projects, and structural ribs integral with said planar base,said planar base being pre-shrunk prior to said structural rib elementsand being pre-stressed thereby.

References Cited in the file of this patent UNITED STATES PATENTS1,845,970 Katz Feb. 16, 1932 2,348,725 Chaplin May 16, 1944 2,375,993Hulbert May 15, 1945 2,838,226 Hartmann June 10, 1958 2,888,183 ReifersMay 26, 1959

1. A MOLDED PULP CARTON INCLUDING A BOTTOM SECTION HAVING OPPOSEDMARGINS, A LID SECTION AND A LOCK FLAP SECTION HINGEDLY CONNECTED TOSAID OPPOSED MARGINS OF SAID BOTTOM SECTION, AND COOPERATING LOCK MEANSON SAID LID AND LOCK FLAP SECTIONS, SAID LOCK MEANS COMPRISING APERTUREMEANS ON SAID LID SECTION AND LATERAL ABUTMENT MEANS ON SAID LOCK FLAPSECTION; THE IMPROVEMENT WHEREIN SAID LOCK FLAP SECTION INCLUDESPRE-STRESSED FIBER PORTION INTERMEDIATELY OF THE HINGE CONNECTION OFSAID LOCK FLAP SECTION AND SAID LATERAL ABUTMENT MEANS FOR RESISTINGTENSION AND BENDING DEFORMATION OF SAID LOCK FLAP SECTION WHEN THECOOPERATING LOCK MEANS IS OPERATED AND MAINTAINING SAID LATERAL ABUTMENTMEANS IN DIMENSIONALLY ORIENTED RELATIONSHIP TO SAID APERTURE MEANS,SAID LOCK FLAP COMPRISING A SUBSTANTIALLY PLANAR BASE HAVING SAIDPRE-STRESSED FIBER PORTION INTEGRALLY FORMED THEREIN, SAID ABUTMENTMEANS PROJECTING OUT OF ONE SURFACE OF SAID PLANAR BASE, AND SAID PLANARBASE INCLUDING PRE-STRESSING RIB ELEMENTS PROJECTING OUT OF ONE SURFACETHEREOF, SAID RIB ELEMENTS EXTENDING BETWEEN THE HINGE CONNECTION OFSAID LOCK FLAP AND TERMINATING ADJACENT SAID LATERAL ABUTMENT MEANS,SAID RIB ELEMENTS BEING DISPOSED SYMMETRICAL TO SAID ABUTMENT MEANS ANDEXTENDING IN SPACED PARALLEL RELATIONSHIP WITH RESPECT TO EACH OTHER ANDIN ANGULAR RELATIONSHIP WITH RESPECT TO SAID HINGE CONNECTION.